The Great Stalacpipe Organ is a unique musical instrument that produces tones of symphonic quality by tapping stalactites in Virginia’s Luray Caverns with electronically-operated rubber mallets.

Recognized as the world’s largest musical instrument, the Great Stalacpipe Organ was created by Leland W. Sprinkle, a mathematician and electronics scientist at the Pentagon. After visiting Luray Caverns with his son and experiencing the organ like sounds of ancient stalactites being tapped, Sprinkle felt inspired to build a one-of-a-kind contraption that could turn these natural tones into playable music. After doing extensive research, he came up with a complex plan for a stalactite tapping instrument, and spent three years just examining each of the caverns’s thousands of hanging limestone columns, looking for the ones that produced specific notes. Only two stalactites were found to be in tune naturally, so he needed to carefully shave thirty-five others to precisely match the musical scale. He then wired a rubber-tipped mallet to each of the selected stalactites and linked them to a four-keyboard console built by the Klann Organ Supply Company of Waynesboro, Virginia, to meet the peculiar needs of this subterranean installation. The music-playing stalactites are spread over 3.5 acres (14,000 m2) of the caverns, so Sprinkle used over five miles of wiring to connect them to the organ console.

But finding the right cave formations and building the Great Stalacpipe Organ was only the beginning. It took 36 years of frustrating research, design and experimentation to bring Leland W. Sprinkle’s dream to its current state of perfection. Today, the unique organ plays a variety of songs, many chosen for their range and deep, resonate tones, that can be heard anywhere within the 64-acre (260,000 m2) confines of the Luray Caverns via a network of loudspeakers. Music is played by an automated system, but it can also be played manually from the console, as Leland Sprinkle himself did for many years. In 2011, the Finnish/Swedish music collective Pepe Deluxé became the first artists to write and record an original composition on The Great Stalacpipe Organ.